Heat dissipating device

ABSTRACT

A heat dissipating device for an electronic element includes a thermoelectric cooler (TEC) attached to the heat conductor, a heat sink attached on the TEC, a fan attached on the heat sink, and a temperature control circuit. The TEC absorbs heat from the electronic element, and transfers the heat to the heat sink. The temperature control circuit receives a rotation speed signal from the fan, when rotation speed of the fan is higher than a given level, the temperature control circuit controls the TEC to cool the electronic element, when rotation speed is lower than the given level, the temperature control circuit controls the TEC to stop cooling the electronic element.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to heat dissipating devices, and particularly to a heat dissipating device for electronic elements.

2. Description of Related Art

During operation of an electronic element of an electronic device such as a central processing unit (CPU) of a computer, a large amount of heat is often produced. The heat must be quickly removed from the CPU to prevent unstable operation or damage to the CPU. Typically, a heat sink is attached to an outer surface of the CPU to absorb the heat from the CPU. The heat absorbed by the heat sink is then dissipated to the ambient air via a fan attached on the heat sink. However, dissipating heat to air is slow and inefficient. In addition, when the temperature of the CPU is high, the fan will keep operating at a high-speed of rotation, which wastes electric power and shortens the lifespan of the fan.

What is desired, therefore, is to provide a heat dissipating device which can efficiently dissipate heat for electronic elements.

SUMMARY OF THE INVENTION

A heat dissipating device for an electronic element includes a thermoelectric cooler (TEC) attached to the heat conductor, a heat sink attached on the TEC, a fan attached on the heat sink, and a temperature control circuit. The TEC absorbs heat from the electronic element, and transfers the heat to the heat sink. The temperature control circuit receives a rotation speed signal from the fan, when rotation speed of the fan is higher than a given level, the temperature control circuit controls the TEC to cool the electronic element, when rotation speed is lower than the given level, the temperature control circuit controls the TEC to stop cooling the electronic element.

Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sketch view of a heat dissipating device in accordance with a preferred embodiment of the present invention, together with a CPU; and

FIG. 2 is a circuit diagram of the heat dissipating device of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, a heat dissipating device 10 in accordance with a preferred embodiment of the present invention is provided for dissipating heat from an electronic element such as a CPU 20 of a computer. The heat dissipating device 10 includes a fan 12, a heat sink 14, a thermoelectric cooler (TEC) 16, a heat conductor 18, and a temperature control circuit 30. The temperature control circuit 30 can be arranged on a free space of a motherboard (not shown) on which the CPU 20 is attached.

The heat conductor 18 is a solid metal cube and attached on a top surface of the CPU 20. A conductive surface of the TEC 16 is attached on a top surface of the heat conductor 18. The heat sink 14 is attached on an opposite surface of the TEC 16. The fan 12 is arranged on the heat sink 14. The heat conductor 18 transfers the heat of the CPU 20 to the TEC 16, the TEC 16 cools the CPU 20 via the heat conductor 18, and transfers the heat from the heat conductor 18 to the heat sink 14, and then the fan 12 transfers the heat from the heat sink 14 to outside.

The fan 12 has a function to detect temperature of the CPU 20, and can adjust its rotation speed according to temperature of the CPU 20 for dissipating heat of the CPU 20 in an energy efficient manner. Typically, rotation speed of the fan 12 has two levels: a lower level and a higher level (more than two levels may be set according to need). When temperature of the CPU 20 is lower than a given value (such as 25° C.), rotation speed of the fan 12 is at the lower level. When temperature of the CPU 20 is higher than the given value, rotation speed of the fan 12 is at the higher level. The temperature control circuit 30 is electrically coupled to the fan 12 and the TEC 16, and receives a rotation speed signal of the fan 12. When rotation speed of the fan 12 is converted from the lower level to the higher level, the control circuit 30 controls the TEC 16 to turn on and the TEC 16 will cool the heat conductor 18. When rotation speed of the fan 12 is converted from the higher level to the lower level, the control circuit 30 controls the TEC 16 to turn off. Thereby, temperature of the CPU 20 is controlled to remain within an optimal range (such as 20° C.-30° C.).

The control circuit 30 includes a first power terminal VCC, a second power terminal VDD, a micro control unit (MCU) M, a first resistor R1, a second resistor R2, a switch SW, a relay K, and an indicator D. The relay K includes an inductance coil J, and a switch S controlled by the inductance coil J. The first power terminal VCC and the second power terminal VDD may be connected to power sources of the motherboard. In this embodiment, the first power terminal VCC is connected to a +12V power source of the motherboard, and the second power terminal VDD is connected to a +3.3V power source of the motherboard. The switch SW is a push-button switch. The MCU M is a PIC10F200 chip produced by Microchip Technology Inc. The indicator D is a light-emitting diode (LED).

An input terminal GP0 of the MCU M is electrically connected to a rotation speed signal output terminal P of the fan 12. Another input terminal GP1 is electrically connected to the second power terminal VDD via the second resistor R2, and electrically connected to ground via the first resistor R1 and the switch SW in parallel. An output terminal GP2 of the MCU M is electrically connected to ground via the inductance coil J of the relay K. Another output terminal GP3 of the MCU M is electrically connected to ground via the indicator D. The first power terminal VCC is connected to a terminal of the TEC 16 via the switch S of the relay K. Another terminal of the TEC 16 is grounded. The +12V power source of the motherboard is used for supplying power to the TEC 16.

A program of the MCU M satisfies that: the input terminal GP0 of the MCU M receives a rotation speed signal from the fan 12, if rotation speed of the fan 12 is at the lower level, the output terminals GP2 and GP3 output a low voltage. Thereby, the relay K is inactive and the switch S is open, and the TEC 16 is not activated. At the same time, the indicator D is unlit. If rotation speed of the fan 12 is at the higher level, the output terminals GP2 and GP3 output a high voltage. Thereby, the relay K is activated, closing the switch S, and the TEC 16 is activated to cool the CPU 20. At the same time, the indicator D will light up. The switch SW is used as a manual override for turning on or off the TEC 16. When the switch SW is pressed, a voltage level of the input terminal GP1 will be change from high to low, causing the output signals of the output terminals GP2 and GP3 to change to an opposite state of their current state, that is, if a current state of the output signals from the output terminals GP2 and GP3 is low, pressing the switch SW will cause the output signals to go high. If a current state of the output signals from the output terminals GP2 and GP3 is high, pressing the switch SW will cause the output signals to go low.

When the CPU 20 starts working, rotation speed of the fan 12 is at the lower level, and the TEC 16 is not activated. If a temperature of the CPU 20 reaches the given value, rotation speed of the fan 12 will be switch from the lower level to the higher level. And then, the TEC 16 is activated by the MCU M to cool the CPU 20. At the same time, the indicator D will light up. When temperature of the CPU 20 is cooled to below the given value, rotation speed of the fan 12 will be returned to the lower level. And then, the TEC 16 stops cooling the CPU 20. At the same time, the indicator D will be turned off. Thus, the fan 12 and the TEC 16 control a temperature of the CPU 20 to remain within an optimal range. If users want to turn on or off the TEC 16 at any time, they can press the switch SW.

In another preferred embodiment of the present invention, it is similar to the foregoing preferred embodiment, except the input terminal GP0 of the MCU M is electrically connected to a temperature signal pin of the CPU 20 on the computer. The program of the MCU is also changed so that: when temperature of the CPU 20 is higher than a given value (such as 25° C.), the MCU controls the TEC 16 to cool the CPU 20, when temperature of the CPU 20 is lower than the given value, the MCU controls the TEC 16 to stop cooling the CPU 20. Thereby, temperature of the CPU 20 is controlled to remain within an optimal range via the TEC 16. The heat sink 14 and the fan 12 can be deleted to saving costs.

It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments. 

1. A heat dissipating device for an electronic element, the heat dissipating device comprising: a thermoelectric cooler (TEC) configured for absorbing heat from the electronic element; a heat sink attached on the TEC for dissipating heat from the TEC; a fan attached on the heat sink for accelerating heat dissipation of the heat sink, and being capable of changing rotation speed thereof according to temperature of the electronic element; and a temperature control circuit receiving a rotation speed signal from the fan, when rotation speed of the fan is higher than a given level, the temperature control circuit controls the TEC to cool the electronic element, when rotation speed is lower than the given level, the temperature control circuit controls the TEC to stop cooling the electronic element.
 2. The heat dissipating device as claimed in claim 1, wherein the temperature control circuit comprises a first power terminal, a micro control unit (MCU), and a relay comprising an inductance coil and a switch, an input terminal of the MCU is electrically connected to a rotation speed signal output terminal of the fan for receiving the rotation speed signal from the fan, an output terminal of the MCU is electrically connected to ground via the inductance coil of the relay, the first power terminal is connected to a terminal of the TEC via the switch of the relay, another terminal of the TEC is grounded.
 3. The heat dissipating device as claimed in claim 2, wherein the temperature control circuit further comprises a second power terminal, a first resistor, a second resistor, and another switch, another input terminal of the MCU is electrically connected to the second power terminal via the second resistor, and electrically connected to ground via the first resistor and the another switch in parallel.
 4. The heat dissipating device as claimed in claim 3, wherein the another switch is a push-button switch.
 5. The heat dissipating device as claimed in claim 2, wherein the temperature control circuit further comprises an indicator for indicating the working status of the TEC, another output terminal of the MCU is electrically connected to ground via the indicator.
 6. The heat dissipating device as claimed in claim 5, wherein the indicator is a light-emitting diode (LED).
 7. The heat dissipating device as claimed in claim 1, further comprising a heat conductor configured to contact the electronic element for collecting heat therefrom, wherein the TEC is attached on the heat conductor and the heat conductor is a solid metal cube.
 8. A heat dissipating device for an electronic element, the heat dissipating device comprising: a heat conductor configured to attach to the electronic element for absorbing heat therefrom; a thermoelectric cooler (TEC) attached to the heat conductor for cooling the electronic element via the heat conductor; and a temperature control circuit detecting temperature of the electronic element, when temperature of the electronic element is higher than a given value, the temperature control circuit controlling the TEC to cool the electronic element, when temperature of the electronic element is lower than the given value, the temperature control circuit controlling the TEC to stop cooling the electronic element.
 9. The heat dissipating device as claimed in claim 8, further comprising: a heat sink attached on the TEC for absorbing heat of the TEC; and a fan attached to the heat sink for transferring the heat from the heat sink to outside.
 10. The heat dissipating device as claimed in claim 8, wherein the temperature control circuit comprises a first power terminal, a micro control unit (MCU), and a relay comprising an inductance coil and a switch, an input terminal of the MCU is electrically connected to a temperature signal pin of the electronic element for detecting a temperature of the electronic element, an output terminal of the MCU is electrically connected to ground via the inductance coil of the relay, the first power terminal is connected to a terminal of the TEC via the switch of the relay, another terminal of the TEC is grounded.
 11. The heat dissipating device as claimed in claim 10, wherein the temperature control circuit further comprises a second power terminal, a first resistor, a second resistor, and another switch, another input terminal of the MCU is electrically connected to the second power terminal via the second resistor, and electrically connected to ground via the first resistor and the another switch, which are connected in parallel.
 12. The heat dissipating device as claimed in claim 1, wherein the first power terminal is connected to a +12V power source of a circuit board on which the electronic element is attached, and the second power terminal is connected to a +3.3V power source of the circuit board.
 13. The heat dissipating device as claimed in claim 11, wherein the switch is a push-button switch.
 14. The heat dissipating device as claimed in claim 10, wherein the temperature control circuit further comprises an indicator for indicating the working status of the TEC, another output terminal of the MCU is electrically connected to ground via the indicator.
 15. The heat dissipating device as claimed in claim 14, wherein the indicator is a light-emitting diode (LED).
 16. A heat dissipating device comprising: a heat conductor attached on an electronic element for absorbing heat therefrom; a thermoelectric cooler (TEC) attached on the heat conductor for cooling the electronic element via the heat conductor; a heat sink attached on the TEC in such a manner that the TEC is sandwiched between the heat conductor and the heat sink; a fan attached to the heat sink and being capable of changing rotation speed thereof according to temperature of the electronic element; and a control circuit configured for controlling the TEC to turn on or off according to the temperature of the electronic element.
 17. The heat dissipating device as claimed in claim 16, wherein when temperature of the electronic element is higher than a given value, the control circuit controls the TEC to turn on to cool the electronic element, and when the temperature of the electronic element is lower than the given value the control circuit controls the TEC to turn off to stop cooling the electronic element.
 18. The heat dissipating device as claimed in claim 17, wherein the fan is capable of adjusting its rotation speed between a lower level and a higher level, when the temperature of the electronic element is higher than the given value, the rotation speed of the fan is at the higher level and when the temperature of the electronic element is lower than the given value, the rotation speed of the fan is at the lower level.
 19. The heat dissipating device as claimed in claim 18, wherein the control circuit comprises a micro control unit (MCU) which is electrically connected to the fan for receiving a rotation speed signal from the fan, and a relay connected to an output terminal of the MCU, the relay being electrically connected between a power source and the TEC for controlling the TEC to turn on or off according to the rotation speed signal of the fan.
 20. The heat dissipating device as claimed in claim 18, wherein the control circuit comprises a micro control unit (MCU) which is electrically connected to the electronic element for detecting the temperature of the electronic element, and a relay connected to an output terminal of the MCU, the relay being electrically connected between a power source and the TEC for controlling the TEC to turn on or off according to the detected temperature. 